![]() Most studies of the neural correlates of temporal discounting have focused on the task instruction period, the point in a trial when the subject is informed of the size of the reward to be delivered and of the delay in time until its delivery ( Berns et al., 2007). In economic behavior, the net payoff for such a cost–benefit dilemma is typically evaluated by integrating the magnitude of the future reward with a hyperbolic discounting function ( Green and Myerson, 2004 Kirby, 1997 Loewenstein et al., 1992). Accordingly, people with low discount rates tend to pursue their long-term goals patiently, whereas people with high discount rates often abandon their goals impulsively and move on ( Janakiraman et al., 2011). All animals, including humans, prefer to receive rewards sooner rather than later, a phenomenon known as temporal discounting ( Frederick et al., 2002 Loewenstein and Prelec, 1993 Mazur, 2001 Vanderveldt et al., 2016). Our individual ability to delay gratification and maintain self-control depends on an internal process that estimates continuously the trade-off between the desirability of the benefit expected and the cost of waiting ( Ainslie, 1975). ![]() How long are you willing to wait for your favorite pastry? Many of us lose patience after about 5 min, while others persevere and keep waiting during longer delays. Imagine you are standing in a queue in front of a bakery. The combination of rewards and time delays into an integrated representation is essential for self-control, the promotion of goal pursuit, and the willingness to bear the costs of time delays. These findings highlight the selective involvement of the dorso-posterior STN in the representation of temporally discounted rewards. Moreover, this encoding was distributed inhomogeneously along the antero-posterior axis of the STN such that the most dorso-posterior-placed neurons represented the temporal discounted value most strongly. This neural encoding of subjective value evolved dynamically across the waiting period that intervened after instruction cue. At the single-neuron and population levels, we found a cost–benefit integration between the desirability of the expected reward and the imposed delay to reward delivery, with STN signals that dynamically combined both attributes of the reward to form a single integrated estimate of value. To address that gap in knowledge, we studied the spiking activity of neurons in the STN of monkeys during a task in which animals were required to remain motionless for varying periods of time in order to obtain food reward. Still uncertain, however, is how that brain structure participates in the dynamically evolving estimation of value that underlies the ability to delay gratification and wait patiently for a gain. ![]() The subthalamic nucleus (STN) is hypothesized to play a central role in neural processes that regulate self-control. ![]()
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